Due to a serial decoding feature of conventional successive cancellation (SC) and SCL decoding methods, long latency of a polar code decoder limits the practical applications of a polar code. To improve decoding latency, simplified successive cancellation list (SSCL) decoding applies appropriate candidate path splitting and path metric updating on certain types of intermediate nodes that correspond to a smaller constituent polar code structure called special nodes without deploying the explicit SCL decoding.
Examples of particular constituent codes that have been explored include Rate-0 code, which corresponds to a constituent code having no information bits; Rate-1 code, which corresponds to a constituent code having only information bits; Rate-R code, which corresponds to a constituent repetition code; and Rate-S code, which corresponds to a single parity check code.
In typical SSCL methods, there is no well-established logic in determining the amount of path splitting in special nodes. In addition, there is no further differentiation within each special node type in terms of processing, which fails to capture their different polarization features in polar decoding.
In general, there is a tradeoff in processing constituent codes between achieved latency reduction/hardware complexity and potential performance degradation. Therefore, operating with the best possible tradeoff, i.e., operating with best performance with given latency reduction/hardware complexity, is an important target in a decoder design.